JP3885113B2 - Combustion furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a combustion heating furnace that uses a high-temperature gas generated by combustion to perform thermal treatment such as surface treatment, heating, annealing, etc., particularly of long materials such as wires, long rods, pipes, etc. About.
[0002]
[Prior art]
Conventionally, a tunnel furnace made of a refractory material is one of the devices used to apply heat treatment such as heating and surface treatment to materials such as wires, rods and pipes made of long metals. Can be mentioned. The tunnel furnace is filled with burned gas by a burner, and the material to be processed moves through the tunnel furnace (for example, Japanese Utility Model Laid-Open No. 3-99755, Japanese Patent Laid-Open No. 54-115607). When the material to be treated is a thin wire, the tunnel furnace is installed in a row, and by winding the wire in a tensioned state along the center of the tunnel furnace at a constant speed, The wire is heat-treated while passing through the tunnel furnace (for example, Japanese Patent Laid-Open No. 7-91842). In these apparatuses, since the furnace is filled with high-temperature burned gas, the furnace wall is formed of a refractory material as a countermeasure. In addition, a heat insulating layer made of a refractory material is provided outside the furnace wall in order to suppress heat loss. In a site where it is difficult to install a tunnel furnace, a method of heating a material to be treated with a flame by a burner is simply performed.
[0003]
In the above-described fixed combustion furnace, the outer size of the apparatus becomes large even when the space available for the heat treatment filled with burned gas is small. Moreover, since it is constructed of refractory bricks, the combustion heating furnace cannot be moved. In addition, there are problems such as time required for production and difficulty in partial modification. Further, depending on the type of refractory material constituting the furnace wall, the refractory material may be worn by internal flow, and the scattered particles and fibers may adversely affect the product. As a simple apparatus for heat treatment, there is a burner that heats an object to be treated by an exposed flame. This type of simple device has the advantage of being extremely inexpensive, but it is difficult to obtain a high temperature and it is difficult to heat uniformly. For this reason, there are problems such that the quality of heat-treated products tends to vary, the oxidizing atmosphere and the reducing atmosphere cannot be controlled, the working efficiency is low, and the fuel consumption per unit processing amount is large.
[0004]
[Problems to be solved by the invention]
Therefore, in a combustion heating furnace that performs heat treatment on the material to be treated, by enabling a compact and stable high-temperature heat treatment gas region to be formed in a region away from the wall surface that forms the combustion chamber, There is a problem to be solved in terms of downsizing and increasing the temperature of the combustion heating furnace.
[0005]
The present invention has been made to solve these problems, and its purpose is much higher than conventional simple methods in terms of temperature and uniformity, working efficiency, fuel consumption, manufacturing cost, and the like. It is an object of the present invention to provide a novel combustion heating furnace that can move and is excellent.
[0006]
[Means for Solving the Problems]
A combustion heating furnace according to the present invention includes a cylindrical combustion chamber whose periphery is defined by a cylindrical side wall surface and whose both ends are opened through an end opening, and a swirling mixture of fuel and air is provided in the combustion chamber. A side wall inlet for allowing a fluid to be formed to flow into the combustion chamber substantially along the cylindrical side wall surface opens to the cylindrical side wall surface, and is formed in the cylindrical combustion chamber by combustion of the mixture swirl flow. A high-temperature burned gas region is formed on the inner side of the continuous flame surface for the thermal treatment of the material to be treated, which is carried in through the end opening.
[0007]
According to this combustion heating furnace, the fluid flows out along the cylindrical wall surface from the side wall inlet opening in the cylindrical side wall surface defining the cylindrical combustion chamber. This fluid forms a swirling mixture of fuel and air in the combustion chamber, and the mixed swirling flow burns to form a cylindrical continuous flame surface that is substantially symmetric with the central axis of the cylindrical combustion chamber. Is formed. A premixed gas having a low temperature exists in the annular portion between the flame surface outside the continuous flame surface and the cylindrical side wall surface, but there is a burned gas region filled with high-temperature combustion gas inside the continuous flame surface. It is formed. A characteristic of this burned gas region is that it has excellent temperature distribution uniformity. The material to be treated is carried through the end opening, inserted into the burned gas region, and placed for a predetermined time, whereby the material to be treated is thermally treated. By utilizing the fact that the cylindrical combustion chamber is open at both ends, the material to be treated is passed through the cylindrical combustion chamber in the axial direction over a predetermined time, so that the length of the heating furnace can be increased even for long materials. It is possible to perform the thermal treatment without being restricted by the length. When the flow rate of the mixture swirl flow and the size and number of side wall inlets are set appropriately, the cylindrical side wall surface that is the combustion chamber wall surface can be sufficiently covered with the low temperature mixture flowing along the wall surface, It is possible to prevent overheating of the cylindrical side wall surface without being touched by a high-temperature flame or burned gas. Applications of the combustion heating furnace include annealing and quenching of metal pipes and round bars, and surface carbonization of logs.
[0008]
In this combustion heating furnace, the fluid may be one type or a plurality of types of fluids selected from a group of fluids consisting of air, gas fuel, a premixed mixture of fuel and air, and air in which fuel particles float. it can. Air is used as an oxidant for burning the fuel. The fuel particles include fine particles of liquid fuel or powdered fuel, and are gasified to form an air-fuel mixture with air. Although the same type of fluid can flow into the combustion chamber from all sidewall inlets, different types of gases may flow into the combustion chamber from differentiated sidewall inlets. In any case, a mixed gas swirl flow in which gasified fuel and air are mixed is formed in the combustion chamber by aligning the inflow direction with respect to the inner surface of the peripheral wall. In order to form a swirling flow, only air is used as the fluid flowing into the combustion chamber along the inner surface of the peripheral wall, and fuel injection means are provided near the opening of the peripheral wall inner surface of the side wall inlet or on the peripheral wall. The mixture swirl flow can be formed inside the combustion chamber by causing the flow of
[0009]
In this combustion heating furnace, the side wall inlet may be an elongated slot extending in the axial direction of the cylindrical combustion chamber. That is, a stable mixture swirl flow is formed in the cylindrical combustion chamber by forming the side wall inlet through which the fluid flows into the cylindrical combustion chamber into an elongated shape (slot) parallel to the central axis of the cylindrical combustion chamber. Is possible. Usually, about two to four slots are provided in the circumferential direction, but when the length of the cylindrical combustion chamber is long, a plurality of slots are preferably arranged in the axial direction.
[0010]
In this combustion heating furnace, the opening of the end of the cylindrical combustion chamber may be limited to an aperture smaller than the inner diameter of the cylindrical side wall surface by the end walls disposed at both ends of the cylindrical combustion chamber. it can. By providing end walls that limit the end openings formed at both ends of the cylindrical combustion chamber, the radiant heat loss from burned gas can be further reduced and higher processing temperatures can be realized, as well as cylindrical combustion The uniformity of the temperature distribution in the burned gas region in the room can be further improved. Further, since a part of the end wall is in contact with the high-temperature gas, the durability can be improved if a part or the whole is made of ceramic or the like.
[0011]
In this combustion heating furnace, the both end portions of the cylindrical combustion chamber can be formed as cylindrical enlarged portions that are expanded with a larger diameter than the inner diameter of the cylindrical side wall surface. Moreover, in this combustion heating furnace, it can be set as the trumpet-shaped expansion part gradually enlarged from the internal diameter of the said cylindrical side wall surface toward the said both ends of the said cylindrical combustion chamber toward the outer side. That is, both ends of the cylindrical combustion chamber are formed as a cylindrical enlarged portion having a larger inner diameter connected through a step or a trumpet-shaped enlarged portion that gradually increases in diameter toward the outside, so that the cylindrical combustion chamber Leakage of the unburned premixed gas along the wall surface can be suppressed, and complete combustion can be easily realized.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic sectional view showing a first embodiment in which a combustion heating furnace according to the present invention is applied to heat treatment of a bar material. FIG. 1A is a schematic cross-sectional view taken along line AA in FIG. 1B, and FIG. 1B is a schematic cross-sectional view taken along broken line BB in FIG. In the combustion heating furnace 10 shown in FIG. 1, a cylindrical combustion chamber (hereinafter simply referred to as “combustion chamber”) 11 is defined by a cylindrical side wall surface (hereinafter simply referred to as “side wall surface”) 12. In addition, both end portions of the combustion chamber 11 are end openings 16 and 16 in which the side wall surface 12 is opened as it is. For example, two side wall inlets 13 are opened on the side wall surface 12. In this embodiment, a premixed mixture 14 of fuel and air is supplied from the side wall inlet 13 to the side wall surface 12 as a fluid. It flows into the combustion chamber 11 toward the tangential direction (both in the same direction in the circumferential direction) and flows along the side wall surface 12 of the combustion chamber 11. The premixed gas 14 that has flowed into the combustion chamber 11 generates a swirling flow within the combustion chamber 11. When the mixture swirl flow is ignited and burned, a cylindrical continuous flame surface 15 is formed on the inner peripheral side of the mixture swirl flow.
[0013]
The annular space 17 between the continuous flame surface 15 and the side wall surface 12 is filled with a premixed gas having a relatively low temperature, while the space inside the continuous flame surface 15 is burned with high temperature burned gas. A gas region 18 is formed. By adjusting the position of the continuous flame surface 15 by adjusting the flow rate of the premixed gas 14, the area of the burned gas region 18 can be adjusted, and the burned gas occupying a relatively large proportion in the combustion chamber 11. Region 18 can be formed. The material 19 to be treated is placed through the region 18 filled with the burned gas, moved in the axial direction of the combustion chamber 11, and subjected to thermal treatment over the movement time. Also, the temperature of the burned gas in region 18 can be controlled by adjusting the fuel / air ratio. Furthermore, if the fuel is excessive, the burned gas can be made reducible.
[0014]
FIG. 2 is a schematic sectional view showing a second embodiment of the combustion heating furnace according to the present invention. 2A is a schematic cross-sectional view taken along line CC in FIG. 2B, and FIG. 2B is a schematic cross-sectional view taken along broken line DD in FIG. About the combustion heating furnace 20 shown in FIG. 2, the same code | symbol is used for the thing equivalent to the components and site | part used for the combustion heating furnace 10 shown in FIG. 1, and those re-explanations are abbreviate | omitted. In the combustion chamber 21 of the combustion heating furnace 20, both end portions are end openings 26 and 26 in which the opening width of the side wall surface 12 is limited by the end wall 23. By setting both ends of the combustion chamber 21 as the end openings 26, 26, the radiant heat loss from the burned gas in the burned gas region 28 can be reduced, and the uniformity of the temperature distribution of the burned gas is improved. Since the end wall 23 is exposed to a high temperature gas, durability is improved if a part or all of the end wall 23 is formed of a refractory material such as ceramic. Even in the case of metal, excellent durability is realized by applying a ceramic thermal barrier coating layer.
[0015]
FIG. 3 is a schematic sectional view showing a third embodiment of the combustion heating furnace according to the present invention. 3A is a schematic cross-sectional view taken along line EE in FIG. 3B, and FIG. 3B is a schematic cross-sectional view taken along broken line FF in FIG. 3A. About the combustion heating furnace 30 shown in FIG. 3, the same code | symbol is used for the thing equivalent to the components and site | parts which are used for the combustion heating furnace 10 shown in FIG. In the combustion heating furnace 30, both end portions of the combustion chamber 31 are cylindrical enlarged portions 33 that have a diameter larger than the inner diameter of the cylindrical side wall surface 32 and are connected to both sides of the side wall surface 32. The end openings 36 and 36 of the combustion chamber 31 are formed by the diameter-expanded opening in which the cylindrical enlarged portion 33 is opened outward. The premixed gas 14 that flows along the wall surface of the combustion chamber 31 generates vortices in the rapidly expanding passage formed by the cylindrical expansion portion 33, and as shown in the burned gas region 38 in a shape that spreads at both ends, The combustion of the premixed gas flowing along the side wall surface 32 is promoted by this vortex.
[0016]
FIG. 4 is a schematic sectional view showing a fourth embodiment of the combustion heating furnace according to the present invention. 4A is a schematic cross-sectional view taken along line GG in FIG. 4B, and FIG. 3B is a schematic cross-sectional view taken along broken line HH in FIG. Also for the combustion heating furnace 40 shown in FIG. 4, the same reference numerals are used for the same parts and parts used in the combustion heating furnace 10 shown in FIG. In the combustion heating furnace 40, both end portions of the combustion chamber 41 are connected to both sides of the side wall surface 42 that is a cylindrical surface, and become a trumpet-shaped enlarged portion 43 that is gradually enlarged from the inner diameter of the side wall surface 42 toward the outside. ing. The end openings 46, 46 of the combustion chamber 41 are formed by openings that are expanded in diameter outside the trumpet-shaped enlarged portion 43. Due to the spread of the trumpet-shaped enlarged portion 43, a burned gas region 48 in which the flame surface spreads in the radial direction at both ends is formed. As a result, the unburned premixed gas 14 can be prevented from flowing out along the wall surface, and complete combustion can be easily realized.
[0017]
As mentioned above, although each Example was described, as a fluid which flows in into the combustion chambers 11-41 from the side wall inlet 13, not only the premixed gas 14 but only air can be made to flow in. In this case, the air-fuel mixture swirl flow and the flame surface 15 can be formed by, for example, injecting liquid fuel or gas fuel provided in the vicinity of the side wall inlet 13 and causing strong interference with the inflowing air. Further, as the fluid flowing into the combustion chambers 11 to 41 from the side wall inlet 13, gas fuel, air in which fuel particulates that can be gasified by heat, etc. are suspended may be used in addition to the premixed gas 14 and air. it can.
[0018]
【The invention's effect】
As described above, the combustion heating furnace according to the present invention includes the cylindrical combustion chamber whose periphery is defined by the cylindrical side wall surface and whose both end portions are opened through the end opening, and is composed of fuel and air in the combustion chamber. A side wall inlet for allowing a fluid for forming a mixture swirl flow to flow into the combustion chamber substantially along the cylindrical side wall surface opens to the cylindrical side wall surface, and the cylindrical shape is formed by combustion of the mixture swirl flow. A high-temperature burned gas region is formed for applying a thermal treatment to the material to be carried through the opening of the end inside the flame surface which is substantially symmetrical with respect to the central axis formed in the combustion chamber. Therefore, by passing the material to be treated through the burned gas region, it is possible to perform continuous thermal treatment with good work efficiency even if the material to be treated is a large, long material. Also, since the cylindrical side wall surface is not overheated because it is covered with a relatively low temperature premixed gas without coming into contact with a high temperature flame or burned gas, the combustion chamber is made of metal without using an expensive heat resistant material. Can be produced. As a result, the combustion heating furnace can be manufactured to be lightweight, simple, and small, and easily movable. Further, the wall surface of the combustion chamber is free from the restriction of high heat resistance, so that the temperature of the burned gas region can be further increased. Furthermore, since the temperature distribution in the area where the burned gas exists is excellent in uniformity and heat loss is small, the combustion heating furnace can save fuel and improve thermal efficiency and manufacturing cost.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a first embodiment of a combustion heating furnace according to the present invention.
FIG. 2 is a schematic sectional view showing a second embodiment of the combustion heating furnace according to the present invention.
FIG. 3 is a schematic cross-sectional view showing a third embodiment of the combustion heating furnace according to the present invention.
FIG. 4 is a schematic sectional view showing a fourth embodiment of the combustion heating furnace according to the present invention.
[Explanation of symbols]
10, 20, 30, 40 Combustion heating furnace 11, 21, 31, 41 Combustion chamber 12, 32, 42 Side wall surface 13 Side wall inlet 14 Premixed gas 15 Continuous flame surface 16, 26, 36, 46 Opening at both ends 17 Annular Space 18, 28, 38, 48 Burned gas region 19 Material 23 End wall 33 Cylindrical enlarged portion 43 Trumpet-like enlarged portion

Claims (6)

A cylindrical combustion chamber having a periphery defined by a cylindrical side wall surface and open at both ends through an end opening is provided, and a fluid for forming a swirling mixture of fuel and air is formed in the combustion chamber. A side wall inlet for flowing into the chamber substantially along the cylindrical side wall surface opens to the cylindrical side wall surface, and is substantially symmetrical with respect to a central axis formed in the cylindrical combustion chamber by the combustion of the mixture swirl flow. A combustion furnace comprising a high-temperature burned gas region for performing a thermal treatment on a workpiece to be carried through the end opening inside a continuous flame surface. 2. The fluid according to claim 1, wherein the fluid is one or a plurality of fluids selected from a group of fluids consisting of air, gaseous fuel, a premixed fuel and air, and air in which fuel particles float. A combustion heating furnace described in 1. The combustion heating furnace according to claim 1, wherein the side wall inlet is an elongated slot extending in an axial direction of the cylindrical combustion chamber. 2. The end opening of the cylindrical combustion chamber is limited to an aperture smaller than the inner diameter of the cylindrical side wall surface by end walls disposed at both ends of the cylindrical combustion chamber. The combustion heating furnace of any one of -3. The said both ends of the said cylindrical combustion chamber are the cylindrical expansion parts expanded from the diameter larger than the internal diameter of the said cylindrical side wall surface, The any one of Claims 1-3 consisting of a cylindrical expansion part. Combustion furnace. The said both ends of the said cylindrical combustion chamber consist of a trumpet-shaped expansion part gradually expanded from the internal diameter of the said cylindrical side wall surface as it goes outside, The any one of Claims 1-3 consisting of Combustion furnace.

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